Table 6 Unadjusted univariate and adjusted multivariate analysis of intraoperative ventilator variables of matched ALI case controls

Variable	Controls (n = 166) (mean (SD))	Cases (n = 83) (mean (SD))	Unadjusted OR (95%CI)	p Value	Adjusted OR (95%CI)*	p Value
First hour
Tidal volume/kg PBW	8.7 (1.7)	8.9 (1.6)	1.08 (0.92–1.27)	0.336	1.03 (0.84–1.26)	0.801
PEEP (cm H₂O)	1.7 (2.2)	1.4 (2.5)	0.94 (0.83–1.07)	0.344	0.89 (0.77–1.04)	0.180
Peak airway pressure (cm H₂O)	19 (4.8)	21 (5.9)	1.10 (1.04–1.15)	<0.001	1.07 (1.02–1.15)	0.045
Respiratory rate (cycles/min)	11 (1.4)	11 (1.3)	1.01 (0.82–1.24)	0.909	1.01 (0.77–1.32)	0.940
Fio₂ (%)	73 (18)	80 (17)	1.03 (1.01–1.04)	0.002	1.00 (0.98–1.03)	0.708

*Adjusted for diabetes, chronic obstructive pulmonary disease, duration of anaesthesia, total red blood cell given, mean arterial blood pressure, smoking status and alcohol use.
ALI, acute lung injury; Fio₂, fraction of inspired oxygen; PBW, predicted body weight; PEEP, positive end expiratory pressure.